1. Field of the Invention
The present invention relates to the fabrication method of thin film resistor, and more particularly to combine forming tungsten-plug and thin film resistor.
2. Description of the Prior Art
Current technology for connecting to thin film resistors falls primarily into two categories. Normally the first utilizes lift-off metallic interconnects, and the second utilizes etched metallic interconnects with an inter-level dielectric and etched vias. Generally resistive thin films often is used as resistors in semiconductor device applications. These resistor films can be sputtered or evapourated onto a wafer and then etched selectively. These resistor films can be delineated by means of a photoresist lift-off process, alternately.
Generally, in the life-off interconnect process, a thin film resistor will be defined by etching or lift-off process. Photoresist is applied and patterned firstly, and then leaving the contact regions of the resistor exposed. Consequentially a metallic layer for the inter-connect is deposited and unwanted portions are lifted off. This process is straightforward but can be used only in limited applications wherein the metallic interconnects can be defined by lift-off. Furthermore, in the etched interconnect process, thin film resistor is formed by etching or lift-off process as well. Photoresist is used to deposit protective metal over the contact regions of the resistor. This sort of metal is not only for the metallic inter-connect, but also is used instead to protect the thin film resistor during subsequent via etching.
After that, an inter-level dielectric is then deposited, followed by patterning and etching of vias in the dielectric, also stopping on the protective metal over the thin film resistor. Finally the metallic interconnect material is deposited and etched.